1. Field of the Invention
Embodiments of the present invention relate to monitoring hydrocarbon fluid flow and, more particularly, monitoring hydrocarbon fluid flow at a tree of a subsea hydrocarbon extraction facility.
2. Description of the Prior Art
Hydrocarbon fluid flowing from an offshore reservoir or well is multiphase in nature in that it contains oil, gas and water and can also contain particulates such as sand. Multiphase meters are used to measure the content of gas, oil and water in the fluid, and other sensors are incorporated to measure the particulates. The sensor equipment is normally mounted on a Christmas tree installed on the seabed, and is usually placed on the Christmas tree after the design has been established. Therefore, the sensor location is often dictated by practical issues rather than the optimum positions for measurements. Current practice is to install a multiphase meter on the Christmas tree with a sensor package positioned at a convenient position. The sensor package usually contains a bundle of sensors. Because the sensors are bundled, the individual sensors may not all be ideally positioned to accurately measure their particular parameter. Some fluid flow measurement techniques require the flow to be conditioned (for example, laminar or turbulent) to be at their optimal accuracy. There is a need for a more accurate method of measurement.
One of the most critical aspects of fluid flow is the effect it has on equipment and fluid pipes due to hydrate formation, wax deposition, slugging and corrosion.
These have a serious effect on the efficiency of the fluid flow, equipment lifetime and through-life maintenance requirements, but can be minimized by taking appropriate remedial action, such as the use of chemical injection to clean the surfaces of the fluid pipes. There is a need for accurately identifying, locating and measuring these effects. However, the availability of sufficiently reliable and accurate sensors has limited the ability to provide the required information. Since the positioning of the sensor package on the Christmas tree is decided after the Christmas tree design has been established, the positioning is not optimized.